//
// detail/impl/descriptor_ops.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_IMPL_DESCRIPTOR_OPS_IPP
#define ASIO_DETAIL_IMPL_DESCRIPTOR_OPS_IPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include <cerrno>
#include "asio/detail/descriptor_ops.hpp"
#include "asio/error.hpp"

#if !defined(ASIO_WINDOWS) \
 && !defined(ASIO_WINDOWS_RUNTIME) \
 && !defined(__CYGWIN__)

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {
        namespace descriptor_ops {

            int open(const char *path, int flags, asio::error_code &ec) {
                int result = ::open(path, flags);
                get_last_error(ec, result < 0);
                return result;
            }

            int open(const char *path, int flags,
                     unsigned mode, asio::error_code &ec) {
                int result = ::open(path, flags, mode);
                get_last_error(ec, result < 0);
                return result;
            }

            int close(int d, state_type &state, asio::error_code &ec) {
                int result = 0;
                if (d != -1) {
                    result = ::close(d);
                    get_last_error(ec, result < 0);

                    if (result != 0
                        && (ec == asio::error::would_block
                            || ec == asio::error::try_again)) {
                        // According to UNIX Network Programming Vol. 1, it is possible for
                        // close() to fail with EWOULDBLOCK under certain circumstances. What
                        // isn't clear is the state of the descriptor after this error. The one
                        // current OS where this behaviour is seen, Windows, says that the socket
                        // remains open. Therefore we'll put the descriptor back into blocking
                        // mode and have another attempt at closing it.
#if defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                        int flags = ::fcntl(d, F_GETFL, 0);
                        if (flags >= 0)
                          ::fcntl(d, F_SETFL, flags & ~O_NONBLOCK);
#else // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                        ioctl_arg_type arg = 0;
                        ::ioctl(d, FIONBIO, &arg);
#endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                        state &= ~non_blocking;

                        result = ::close(d);
                        get_last_error(ec, result < 0);
                    }
                }

                return result;
            }

            bool set_user_non_blocking(int d, state_type &state,
                                       bool value, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return false;
                }

#if defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                int result = ::fcntl(d, F_GETFL, 0);
                get_last_error(ec, result < 0);
                if (result >= 0)
                {
                  int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
                  result = ::fcntl(d, F_SETFL, flag);
                  get_last_error(ec, result < 0);
                }
#else // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                ioctl_arg_type arg = (value ? 1 : 0);
                int result = ::ioctl(d, FIONBIO, &arg);
                get_last_error(ec, result < 0);
#endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)

                if (result >= 0) {
                    if (value)
                        state |= user_set_non_blocking;
                    else {
                        // Clearing the user-set non-blocking mode always overrides any
                        // internally-set non-blocking flag. Any subsequent asynchronous
                        // operations will need to re-enable non-blocking I/O.
                        state &= ~(user_set_non_blocking | internal_non_blocking);
                    }
                    return true;
                }

                return false;
            }

            bool set_internal_non_blocking(int d, state_type &state,
                                           bool value, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return false;
                }

                if (!value && (state & user_set_non_blocking)) {
                    // It does not make sense to clear the internal non-blocking flag if the
                    // user still wants non-blocking behaviour. Return an error and let the
                    // caller figure out whether to update the user-set non-blocking flag.
                    ec = asio::error::invalid_argument;
                    return false;
                }

#if defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                int result = ::fcntl(d, F_GETFL, 0);
                get_last_error(ec, result < 0);
                if (result >= 0)
                {
                  int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
                  result = ::fcntl(d, F_SETFL, flag);
                  get_last_error(ec, result < 0);
                }
#else // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
                ioctl_arg_type arg = (value ? 1 : 0);
                int result = ::ioctl(d, FIONBIO, &arg);
                get_last_error(ec, result < 0);
#endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)

                if (result >= 0) {
                    if (value)
                        state |= internal_non_blocking;
                    else
                        state &= ~internal_non_blocking;
                    return true;
                }

                return false;
            }

            std::size_t sync_read(int d, state_type state, buf *bufs,
                                  std::size_t count, bool all_empty, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return 0;
                }

                // A request to read 0 bytes on a stream is a no-op.
                if (all_empty) {
                    ec.assign(0, ec.category());
                    return 0;
                }

                // Read some data.
                for (;;) {
                    // Try to complete the operation without blocking.
                    signed_size_type bytes = ::readv(d, bufs, static_cast<int>(count));
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes > 0)
                        return bytes;

                    // Check for EOF.
                    if (bytes == 0) {
                        ec = asio::error::eof;
                        return 0;
                    }

                    // Operation failed.
                    if ((state & user_set_non_blocking)
                        || (ec != asio::error::would_block
                            && ec != asio::error::try_again))
                        return 0;

                    // Wait for descriptor to become ready.
                    if (descriptor_ops::poll_read(d, 0, ec) < 0)
                        return 0;
                }
            }

            std::size_t sync_read1(int d, state_type state, void *data,
                                   std::size_t size, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return 0;
                }

                // A request to read 0 bytes on a stream is a no-op.
                if (size == 0) {
                    ec.assign(0, ec.category());
                    return 0;
                }

                // Read some data.
                for (;;) {
                    // Try to complete the operation without blocking.
                    signed_size_type bytes = ::read(d, data, size);
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes > 0)
                        return bytes;

                    // Check for EOF.
                    if (bytes == 0) {
                        ec = asio::error::eof;
                        return 0;
                    }

                    // Operation failed.
                    if ((state & user_set_non_blocking)
                        || (ec != asio::error::would_block
                            && ec != asio::error::try_again))
                        return 0;

                    // Wait for descriptor to become ready.
                    if (descriptor_ops::poll_read(d, 0, ec) < 0)
                        return 0;
                }
            }

            bool non_blocking_read(int d, buf *bufs, std::size_t count,
                                   asio::error_code &ec, std::size_t &bytes_transferred) {
                for (;;) {
                    // Read some data.
                    signed_size_type bytes = ::readv(d, bufs, static_cast<int>(count));
                    get_last_error(ec, bytes < 0);

                    // Check for end of stream.
                    if (bytes == 0) {
                        ec = asio::error::eof;
                        return true;
                    }

                    // Check if operation succeeded.
                    if (bytes > 0) {
                        bytes_transferred = bytes;
                        return true;
                    }

                    // Retry operation if interrupted by signal.
                    if (ec == asio::error::interrupted)
                        continue;

                    // Check if we need to run the operation again.
                    if (ec == asio::error::would_block
                        || ec == asio::error::try_again)
                        return false;

                    // Operation failed.
                    bytes_transferred = 0;
                    return true;
                }
            }

            bool non_blocking_read1(int d, void *data, std::size_t size,
                                    asio::error_code &ec, std::size_t &bytes_transferred) {
                for (;;) {
                    // Read some data.
                    signed_size_type bytes = ::read(d, data, size);
                    get_last_error(ec, bytes < 0);

                    // Check for end of stream.
                    if (bytes == 0) {
                        ec = asio::error::eof;
                        return true;
                    }

                    // Check if operation succeeded.
                    if (bytes > 0) {
                        bytes_transferred = bytes;
                        return true;
                    }

                    // Retry operation if interrupted by signal.
                    if (ec == asio::error::interrupted)
                        continue;

                    // Check if we need to run the operation again.
                    if (ec == asio::error::would_block
                        || ec == asio::error::try_again)
                        return false;

                    // Operation failed.
                    bytes_transferred = 0;
                    return true;
                }
            }

            std::size_t sync_write(int d, state_type state, const buf *bufs,
                                   std::size_t count, bool all_empty, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return 0;
                }

                // A request to write 0 bytes on a stream is a no-op.
                if (all_empty) {
                    ec.assign(0, ec.category());
                    return 0;
                }

                // Write some data.
                for (;;) {
                    // Try to complete the operation without blocking.
                    signed_size_type bytes = ::writev(d, bufs, static_cast<int>(count));
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes > 0)
                        return bytes;

                    // Operation failed.
                    if ((state & user_set_non_blocking)
                        || (ec != asio::error::would_block
                            && ec != asio::error::try_again))
                        return 0;

                    // Wait for descriptor to become ready.
                    if (descriptor_ops::poll_write(d, 0, ec) < 0)
                        return 0;
                }
            }

            std::size_t sync_write1(int d, state_type state, const void *data,
                                    std::size_t size, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return 0;
                }

                // A request to write 0 bytes on a stream is a no-op.
                if (size == 0) {
                    ec.assign(0, ec.category());
                    return 0;
                }

                // Write some data.
                for (;;) {
                    // Try to complete the operation without blocking.
                    signed_size_type bytes = ::write(d, data, size);
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes > 0)
                        return bytes;

                    // Operation failed.
                    if ((state & user_set_non_blocking)
                        || (ec != asio::error::would_block
                            && ec != asio::error::try_again))
                        return 0;

                    // Wait for descriptor to become ready.
                    if (descriptor_ops::poll_write(d, 0, ec) < 0)
                        return 0;
                }
            }

            bool non_blocking_write(int d, const buf *bufs, std::size_t count,
                                    asio::error_code &ec, std::size_t &bytes_transferred) {
                for (;;) {
                    // Write some data.
                    signed_size_type bytes = ::writev(d, bufs, static_cast<int>(count));
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes >= 0) {
                        bytes_transferred = bytes;
                        return true;
                    }

                    // Retry operation if interrupted by signal.
                    if (ec == asio::error::interrupted)
                        continue;

                    // Check if we need to run the operation again.
                    if (ec == asio::error::would_block
                        || ec == asio::error::try_again)
                        return false;

                    // Operation failed.
                    bytes_transferred = 0;
                    return true;
                }
            }

            bool non_blocking_write1(int d, const void *data, std::size_t size,
                                     asio::error_code &ec, std::size_t &bytes_transferred) {
                for (;;) {
                    // Write some data.
                    signed_size_type bytes = ::write(d, data, size);
                    get_last_error(ec, bytes < 0);

                    // Check if operation succeeded.
                    if (bytes >= 0) {
                        bytes_transferred = bytes;
                        return true;
                    }

                    // Retry operation if interrupted by signal.
                    if (ec == asio::error::interrupted)
                        continue;

                    // Check if we need to run the operation again.
                    if (ec == asio::error::would_block
                        || ec == asio::error::try_again)
                        return false;

                    // Operation failed.
                    bytes_transferred = 0;
                    return true;
                }
            }

#if defined(ASIO_HAS_FILE)

            std::size_t sync_read_at(int d, state_type state, uint64_t offset,
                buf* bufs, std::size_t count, bool all_empty, asio::error_code& ec)
            {
              if (d == -1)
              {
                ec = asio::error::bad_descriptor;
                return 0;
              }

              // A request to read 0 bytes on a stream is a no-op.
              if (all_empty)
              {
                ec.assign(0, ec.category());
                return 0;
              }

              // Read some data.
              for (;;)
              {
                // Try to complete the operation without blocking.
                signed_size_type bytes = ::preadv(d, bufs, static_cast<int>(count), offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes > 0)
                  return bytes;

                // Check for EOF.
                if (bytes == 0)
                {
                  ec = asio::error::eof;
                  return 0;
                }

                // Operation failed.
                if ((state & user_set_non_blocking)
                    || (ec != asio::error::would_block
                      && ec != asio::error::try_again))
                  return 0;

                // Wait for descriptor to become ready.
                if (descriptor_ops::poll_read(d, 0, ec) < 0)
                  return 0;
              }
            }

            std::size_t sync_read_at1(int d, state_type state, uint64_t offset,
                void* data, std::size_t size, asio::error_code& ec)
            {
              if (d == -1)
              {
                ec = asio::error::bad_descriptor;
                return 0;
              }

              // A request to read 0 bytes on a stream is a no-op.
              if (size == 0)
              {
                ec.assign(0, ec.category());
                return 0;
              }

              // Read some data.
              for (;;)
              {
                // Try to complete the operation without blocking.
                signed_size_type bytes = ::pread(d, data, size, offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes > 0)
                  return bytes;

                // Check for EOF.
                if (bytes == 0)
                {
                  ec = asio::error::eof;
                  return 0;
                }

                // Operation failed.
                if ((state & user_set_non_blocking)
                    || (ec != asio::error::would_block
                      && ec != asio::error::try_again))
                  return 0;

                // Wait for descriptor to become ready.
                if (descriptor_ops::poll_read(d, 0, ec) < 0)
                  return 0;
              }
            }

            bool non_blocking_read_at(int d, uint64_t offset, buf* bufs, std::size_t count,
                asio::error_code& ec, std::size_t& bytes_transferred)
            {
              for (;;)
              {
                // Read some data.
                signed_size_type bytes = ::preadv(d, bufs, static_cast<int>(count), offset);
                get_last_error(ec, bytes < 0);

                // Check for EOF.
                if (bytes == 0)
                {
                  ec = asio::error::eof;
                  return true;
                }

                // Check if operation succeeded.
                if (bytes > 0)
                {
                  bytes_transferred = bytes;
                  return true;
                }

                // Retry operation if interrupted by signal.
                if (ec == asio::error::interrupted)
                  continue;

                // Check if we need to run the operation again.
                if (ec == asio::error::would_block
                    || ec == asio::error::try_again)
                  return false;

                // Operation failed.
                bytes_transferred = 0;
                return true;
              }
            }

            bool non_blocking_read_at1(int d, uint64_t offset, void* data, std::size_t size,
                asio::error_code& ec, std::size_t& bytes_transferred)
            {
              for (;;)
              {
                // Read some data.
                signed_size_type bytes = ::pread(d, data, size, offset);
                get_last_error(ec, bytes < 0);

                // Check for EOF.
                if (bytes == 0)
                {
                  ec = asio::error::eof;
                  return true;
                }

                // Check if operation succeeded.
                if (bytes > 0)
                {
                  bytes_transferred = bytes;
                  return true;
                }

                // Retry operation if interrupted by signal.
                if (ec == asio::error::interrupted)
                  continue;

                // Check if we need to run the operation again.
                if (ec == asio::error::would_block
                    || ec == asio::error::try_again)
                  return false;

                // Operation failed.
                bytes_transferred = 0;
                return true;
              }
            }

            std::size_t sync_write_at(int d, state_type state, uint64_t offset,
                const buf* bufs, std::size_t count, bool all_empty,
                asio::error_code& ec)
            {
              if (d == -1)
              {
                ec = asio::error::bad_descriptor;
                return 0;
              }

              // A request to write 0 bytes on a stream is a no-op.
              if (all_empty)
              {
                ec.assign(0, ec.category());
                return 0;
              }

              // Write some data.
              for (;;)
              {
                // Try to complete the operation without blocking.
                signed_size_type bytes = ::pwritev(d,
                    bufs, static_cast<int>(count), offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes > 0)
                  return bytes;

                // Operation failed.
                if ((state & user_set_non_blocking)
                    || (ec != asio::error::would_block
                      && ec != asio::error::try_again))
                  return 0;

                // Wait for descriptor to become ready.
                if (descriptor_ops::poll_write(d, 0, ec) < 0)
                  return 0;
              }
            }

            std::size_t sync_write_at1(int d, state_type state, uint64_t offset,
                const void* data, std::size_t size, asio::error_code& ec)
            {
              if (d == -1)
              {
                ec = asio::error::bad_descriptor;
                return 0;
              }

              // A request to write 0 bytes on a stream is a no-op.
              if (size == 0)
              {
                ec.assign(0, ec.category());
                return 0;
              }

              // Write some data.
              for (;;)
              {
                // Try to complete the operation without blocking.
                signed_size_type bytes = ::pwrite(d, data, size, offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes > 0)
                  return bytes;

                // Operation failed.
                if ((state & user_set_non_blocking)
                    || (ec != asio::error::would_block
                      && ec != asio::error::try_again))
                  return 0;

                // Wait for descriptor to become ready.
                if (descriptor_ops::poll_write(d, 0, ec) < 0)
                  return 0;
              }
            }

            bool non_blocking_write_at(int d, uint64_t offset,
                const buf* bufs, std::size_t count,
                asio::error_code& ec, std::size_t& bytes_transferred)
            {
              for (;;)
              {
                // Write some data.
                signed_size_type bytes = ::pwritev(d,
                    bufs, static_cast<int>(count), offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes >= 0)
                {
                  bytes_transferred = bytes;
                  return true;
                }

                // Retry operation if interrupted by signal.
                if (ec == asio::error::interrupted)
                  continue;

                // Check if we need to run the operation again.
                if (ec == asio::error::would_block
                    || ec == asio::error::try_again)
                  return false;

                // Operation failed.
                bytes_transferred = 0;
                return true;
              }
            }

            bool non_blocking_write_at1(int d, uint64_t offset,
                const void* data, std::size_t size,
                asio::error_code& ec, std::size_t& bytes_transferred)
            {
              for (;;)
              {
                // Write some data.
                signed_size_type bytes = ::pwrite(d, data, size, offset);
                get_last_error(ec, bytes < 0);

                // Check if operation succeeded.
                if (bytes >= 0)
                {
                  bytes_transferred = bytes;
                  return true;
                }

                // Retry operation if interrupted by signal.
                if (ec == asio::error::interrupted)
                  continue;

                // Check if we need to run the operation again.
                if (ec == asio::error::would_block
                    || ec == asio::error::try_again)
                  return false;

                // Operation failed.
                bytes_transferred = 0;
                return true;
              }
            }

#endif // defined(ASIO_HAS_FILE)

            int ioctl(int d, state_type &state, long cmd,
                      ioctl_arg_type *arg, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                int result = ::ioctl(d, cmd, arg);
                get_last_error(ec, result < 0);

                if (result >= 0) {
                    // When updating the non-blocking mode we always perform the ioctl syscall,
                    // even if the flags would otherwise indicate that the descriptor is
                    // already in the correct state. This ensures that the underlying
                    // descriptor is put into the state that has been requested by the user. If
                    // the ioctl syscall was successful then we need to update the flags to
                    // match.
                    if (cmd == static_cast<long>(FIONBIO)) {
                        if (*arg) {
                            state |= user_set_non_blocking;
                        } else {
                            // Clearing the non-blocking mode always overrides any internally-set
                            // non-blocking flag. Any subsequent asynchronous operations will need
                            // to re-enable non-blocking I/O.
                            state &= ~(user_set_non_blocking | internal_non_blocking);
                        }
                    }
                }

                return result;
            }

            int fcntl(int d, int cmd, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                int result = ::fcntl(d, cmd);
                get_last_error(ec, result < 0);
                return result;
            }

            int fcntl(int d, int cmd, long arg, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                int result = ::fcntl(d, cmd, arg);
                get_last_error(ec, result < 0);
                return result;
            }

            int poll_read(int d, state_type state, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                pollfd fds;
                fds.fd = d;
                fds.events = POLLIN;
                fds.revents = 0;
                int timeout = (state & user_set_non_blocking) ? 0 : -1;
                int result = ::poll(&fds, 1, timeout);
                get_last_error(ec, result < 0);
                if (result == 0)
                    if (state & user_set_non_blocking)
                        ec = asio::error::would_block;
                return result;
            }

            int poll_write(int d, state_type state, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                pollfd fds;
                fds.fd = d;
                fds.events = POLLOUT;
                fds.revents = 0;
                int timeout = (state & user_set_non_blocking) ? 0 : -1;
                int result = ::poll(&fds, 1, timeout);
                get_last_error(ec, result < 0);
                if (result == 0)
                    if (state & user_set_non_blocking)
                        ec = asio::error::would_block;
                return result;
            }

            int poll_error(int d, state_type state, asio::error_code &ec) {
                if (d == -1) {
                    ec = asio::error::bad_descriptor;
                    return -1;
                }

                pollfd fds;
                fds.fd = d;
                fds.events = POLLPRI | POLLERR | POLLHUP;
                fds.revents = 0;
                int timeout = (state & user_set_non_blocking) ? 0 : -1;
                int result = ::poll(&fds, 1, timeout);
                get_last_error(ec, result < 0);
                if (result == 0)
                    if (state & user_set_non_blocking)
                        ec = asio::error::would_block;
                return result;
            }

        } // namespace descriptor_ops
    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // !defined(ASIO_WINDOWS)
//   && !defined(ASIO_WINDOWS_RUNTIME)
//   && !defined(__CYGWIN__)

#endif // ASIO_DETAIL_IMPL_DESCRIPTOR_OPS_IPP
